Wireless communication systems are utilized today in a wide variety of applications. Providing diverse types of communication, including voice, data transfer, and web browsing, these wireless systems have become nearly ubiquitous in our daily lives.
In general, signal strength is a critical factor in establishing a communication link with good quality of service. Decreased signal strength can affect the performance of a broadband communication system substantially, particularly where many users are attempting to access the interact, for example, via a single access point, as is common on seagoing vessels such as cruise ships.
Although land-based wireless communication systems may experience some limited signal degradation due to environmental interference, these issues are exacerbated in a marine environment, particularly where signals must be transmitted over long distances. When radio waves come in contact with the ground, for example, they are mostly absorbed and dispersed. With respect to signal propagation over a body of water, however, weather and environmental factors may cause significant inference with the signal. High humidity over a body′ of water can cause significant issues with scatter, which increases noise, and the surface of the body of water may reflect and/or refract the signal. Thus, when traveling over water, radio waves tend to bounce, skip, reflect and refract, and due to the curvature of the earth, it is inevitable that some radio waves will hit the water's surface. As such, transmission of a signal over a long distance in a marine environment can involve significant waveform distortion and interference from the signal's hitting the water. Another problem encountered when transmitting a signal over a long distance is that the beam of the radio wave expands greatly (e.g., a beam that is 1.5 inches wide/tall at the transmitting antenna will expand to over 300 ft. at 50 miles away); therefore, some of that waveform will be lost to the sea. These issues can cause loss of connectivity or performance, particularly in systems utilizing a single, high-performance beam.
Currently available systems for providing internet access to seagoing vessels via land-based transceivers tend to perform poorly at long distances, as these systems utilize a single connection with a 64-QAM modulation scheme. Using that technique, even an 11 Mbs connection is not likely to be stable, or even possible, if the signal level is any lower than −78 dBm. Furthermore, even at short distances (e.g., when a seagoing vessel is in port), other vessels may simultaneously be competing for the same bandwidth on the same channel on the same frequency, resulting in poor service for all. A crowded port may also generate a high radio noise level, which can cause additional performance issues.
Thus, most maritime data communication requirements are currently addressed using satellite connections. Currently available satellite systems typically provide internet access at little more than dial-up speeds, however, as limited bandwidth and latency issues reduce performance. The limited internet access currently offered by cruise ships, for example, discourages use due to its slow speeds and relative cost. Moreover, these satellite connections were designed for much slower asynchronous connections, which are insufficient for today's increasing data demands. Streams and high-density data, such as pictures and graphics, are already compressed. Thus, the caching and compression methods used in the past to hide poor throughput on satellite systems are not effective on the newer forms of data, which involve increasingly dense data types. As the evolution of the networks continue, more data is originating from the clients, and, therefore, the “up” bandwidth is as important as the “down,” None of the current satellite systems provide symmetrical network connections today. Therefore, until such time as satellite systems deploy that can meet these demands, an alternative is required.